Embodiments of the inventive concept relate to a nonvolatile memory device and a method of writing data in a nonvolatile memory system including the nonvolatile memory device, and more particularly, to a nonvolatile memory device including a nonvolatile memory cell and a method of writing data in a nonvolatile memory system including the nonvolatile memory device.
A nonvolatile memory device is able to retain stored data even when no power is provided by a power supply. Flash memory, which is an example of a nonvolatile memory device, may include a nonvolatile memory cell that is capable of electrically writing or erasing data, and the nonvolatile memory cell may include a floating-gate transistor. The nonvolatile memory cell may store data by controlling a threshold voltage of the floating-gate transistor.
The amount of data that may be stored in the nonvolatile memory cell may be increased by precisely controlling the threshold voltage of the floating-gate transistor. For example, when the threshold voltage of the floating-gate transistor is controlled to have two different values, one nonvolatile memory cell may store one bit. However, when the threshold voltage of the floating-gate transistor is controlled to have four different values, the one nonvolatile memory cell may store two bits.